1. Continued studies of mutant mouse which stores cystine in lysosomes as do cystinotic patients; anamolies in cholesterol metabolism uncovered similar to: a) Niemann-Pick C cells which show lysosomal storage of cholesterol and lack of intracellular cholesterol esterification. b) Niemann-Pick D cells which do not store cholesterol but do show a lack of cholesterol esterification. 2. Studies of cholesterol metabolism in Niemann-Pick C and D, and cystinotic fibroblasts. 3. Characterization of cystinotic cell metallothionein present in a 2-fold excess in cystinotic versus normal fibroblasts.